A New York City art gallery is standing by a work hanging on its door that accuses police of lynching African-Americans, despite renewed criticism in the wake of last week's murder of five cops in Dallas.

The Jack Shainman Gallery in Manhattan is displaying a flag above its front door that says "A Man was Lynched by Police Yesterday" -- an artist's representation of a similar banner used by the NAACP to bring attention to violence perpetrated against blacks during the Jim Crow era.

The banner -- created by artist Dread Scott -- was put up in Manhattan's Union Square area last week as hundreds of people protested the recent police killings of Alton Sterling and Philando Castile. But the gallery decided to keep the flag flying after a deadly sniper attack on Dallas officers on Friday that left five dead and seven wounded. 

"The gallery has not and will not reconsider the hanging of Dread Scott's flag," the Jack Shainman Gallery said in an email to FoxNews.com. "It will remain as part of the For Freedoms exhibition for the duration of the show."

In an interview with PBS, the artist defended his work, saying, “I really felt that the NAACP’s banner needed to be updated … It’s an indictment of this whole system.”

Critics, however, say the banner -- while it is freedom of speech -- is the wrong sign to hang after the deadly ambush of five Dallas officers. 

“Vicious, insensitive lies pretending to be art is never helpful to anyone but is particularly repulsive during this time of national tragedy," a former New York City police official told FoxNews.com Monday.

The NAACP flew a flag outside of its New York City headquarters from 1920 to 1938 that read, “A man was lynched yesterday.” The flag was meant to be a disturbing reminder of the senseless murders of black people by mobs around the nation.

But the banner flying outside the Jack Shainman Gallery -- meant to be a version of the old NAACP flag -- reads, “A man was lynched by police yesterday.”

The flag is not the only anti-cop art exhibit to draw attention in recent years.

New York City's largest police union last year blasted an art installation at the Flux Factory in Queens that invites people to experience a simulated death at the hands of police.

“This so-called ‘art project’ is based upon a lie and perpetuates a falsehood about police officers and their use of force,” Patrick Lynch, president of the Patrolmen’s Benevolent Association, said of the exhibit, called "Hands Up," the New York Daily News reported.

"If art is supposed to enlighten and uplift, this piece of crap doesn’t qualify," Lynch told the paper.